Any foundation experts out there?

[HT413]

So my real question and reason for this thread is, what do you think of the footer and floor being poured as 1? Would the floor be prone to crack along the footer?

Monolithic is definitely faster. I've done that a few times in big town house developments. They definitely crack, but probably not much more than traditional. I would put control joints in 24 hours after the pour just to tell it where to crack. Probably break it into 8x8 or 10x10 sections. That should control any cracking.

How much slope does the ground have within the building envelope?

Will the slab and footer all be on native soil, or will you be placing some fill to get a corner / side up?

 

[HT413]

This is what I've seen as a "garage foundation"??? Just doesn't seam right being that shallow??? An insulated 36" deep footer I would think would keep more cold from getting under the

That's just a conceptual illustration, the idea is just continue the fitting down as far as necessary in your neck of the woods.

 

[747mopar]

Thanks again HT, the excavator should be out this week to put a lazer on it but I'm going to guess there's at least a 6ft drop in the 56 length (32 width on a footer and 24' poll barn style) . I'm not planning on using any fill on the workshop side that gets the footer but instead dig it all level, the lower 24' garage will be poll barn style and I may fill some of it with gravel? I'm contemplating whether I want the concrete wall high enough to retain the dirt or to just put a retaining wall in? The upper side that will need a lot of digging puts the garage 5ft from a 10ft tall X 30ft wide bolder, if we dig down and find that boulder is well into the ground than there's the retaining wall lol.

Been doing some figuring and think the best option might be a 12" wide footer, just form 12" above grade with 2X12s and pour it full then the floor. Minimal difference in price a with a single story garage on this rocky hard ground it's more than adequate.

 

[747mopar]

I had a friend go the plywood route thinking he could reuse it elsewhere....which proved to be wrong. It drew a lot of moisture, warped a little and had a lot of concrete stick to it....and was a lot of work to shore up. In the end he had to just dispose of the wood. If it's a draw in costs between the plywood and renting forms....I think the form route would end up saving you some labor and you wouldn't have to deal with the scrap wood.

That's what my experience was but had never tried lubing it or anything else. Pretty sure I'm not going that route.

 

[Mike67]

That's what my experience was but had never tried lubing it or anything else. Pretty sure I'm not going that route.

I know when they do tilt wall construction before they pour the walls they spray a releasing agent on the slab. This is to prevent the wall from sticking to the slab after it has cured so they can lift it.... Dont know if it would work on plywood though...
I'm no engineer, nor did I sleep at a holiday inn but I've been on big pours, slabs to high rise buildings and from what I've seen, all concrete cracks....its inherent to the curing process. There is a lot of heat generated.
HT might be able to elaborate more...my concern in your area would be moisture sealing it after words, just to keep any water out that might get in a crack & freeze....we don't have to worry about that to much down here...
Good luck!

 

[Don selleck]

I'm moving my garage from ten feet from the road to next to my house, (getting out in the winter time was the theory behind that madness back in the day. I'm plan on taking my kubota which has a small backhoe attachment and digging(they have rentals where you can get one) a trench 42" (code in michigan) deep the width of the bucket, without disturbing the ground that the footer is going to set on, may be a problem for your sandstone issue, but u can make it a little deeper if you need to remove large stones just figure a little more concrete or fill and tamp the dirt down level. setting a level string line just on the inside of foundation suspended about a foot above so i can check the level of footer by measuring down to the top of the pour. calling the concrete truck and having them fill the trench unfortunatly in your case, in avoidance of the cement blocks you'll need to put at least one coarse of block, I'm planning on two, then hammer drill holes thru hole in top of block into the footer, dropping in some threaded rod, and filling the core holes of the block with mortar This leaves a nice looking exposed block foundation to set your sill plate on and bolt it down. the dirt acts as the form, seen this done many time up here. also seperates the footer from the garage floor when u pour it. good luck with however you do it. P.S. water is the enemy, make sure it will flow away on all sides, my current one built by someone else in the side of a hill, floods in the spring and heavy rains.

 

[747mopar]

Sounds like what I'm leaning towards but instead of block I'll form a foot above grade so it will all get poured together then drop lag bolts in the concrete.

 

[Bladecutter]

Sounds like what I'm leaning towards but instead of block I'll form a foot above grade so it will all get poured together then drop lag bolts in the concrete.

i'm not a construction guy at all, at the expense of sounding stoopid...are You doing a network of rebar?? The more web of rebar done will result in less cracking wont it?

 

[747mopar]

I've tried the reinforced concrete before and wasn't impressed so I just rebar everything now, a 2 foot square pattern is usually plenty for a floor. Rebar will help prevent cracks if placed in the right areas like towards the bottom of the floor (has to stretch the bar in order to sink) but where it really helps is keeping cracks from shifting.

 

[gdrill]

I built mine similar to what HT and Don described. I cut a trench all the way around my perimeter and as an extra I put 2" blue styrofoam insulation on the outside edge. Then I filled the inside with concrete to about 6" below slab. Effectively I used undisturbed ground and foam as my form. I did put rebar throughout this. I tied 90 degree bent bar to the footing bar sticking up to tie my slab to. My trench was 48" deep. My thickened slab is 32' x 54' x 6" with 13" x 30" around the edge as the thickened portion. On top of this I went around the outside of the whole building with a 5' sidewalk with 2" x 4' of insulation laid under it against the building. This was slightly overkill for the requirements around here, but I didn't want any frost action taking place. My slab has only 2 hairline cracks in it. One right beside my radiant manifold and one in front of the overhead door. They showed up the first year and nothing has happened since.

 

[747mopar]

Very nice work!

 

[747mopar]

I hate to ask how much you have in the pex and foam? Is that foam built specifically for radiant floor installations?

 

[MarPar]

 

[gdrill]

Actually I had lost track of my receipts for the radiant supplies, but you made me do some digging and I found the quote! The foam is specific as the pex lays into notches cut into raised ribs on it. Then there were some little white push in clips that went over the pex randomly stuck into the foam. You can see them in the pic. That made it very easy to lay out and kept it in place while pouring. Below is the list of material with pricing. This is CAD.

1 roll 1500’ 5/8” Viega oxygen barrier PEX………………..………..…………….. $950.00

1 roll 500’ 5/8” Viega oxygen barrier PEX……..…………..………..…………….. $340.00

1 - 5 outlet Viega SS balancing manifold ..………………..………..…………….. $480.00

10 Viega 5/8” manifold compression fittings ($7.10 ea.) …………………...…… $71.00

1 Viega SS manifold isolation valve set ……………………………………………. $72.25

1 bag (500) Styrofoam staples ……………………………………………………….. $85.00

1 roll Rehau protection sleeving …………………………………………………….. $64.00

10 - 5/8” PEX bend supports ($6.25 ea) …………………………………………….. $62.50

5 bundles beaver plastic insulation (320Sq. feet at $265.00 a bundle) …….. $1325.00